Improvement in pistons amd packings



2 Sheets--Sheet1. A. K. RIDER.

Pistons and Packings, No, 143,255, Patented September30,l873.

2 Sheets--Sheet2. A. K. R l D ER.

Pistons and Packings.

, PatentedSeptember30,l87.3.

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AM. PHHlD-LITHOGWAP/f/C ta. M X (USHER/V55 Muasss/ UNITED STATES PATENTFFICE.

ALEXANDER K. RIDER, OF NEW YORK, N. Y.

IMPROVEMENT IN PISTONS AND PACKINGS.

v Specification forming part of Letters Patent No. 143,255, datedSeptember 30, 1873; application filed March 29, 1873.

To all whom it may concern:

Be it known that I, ALEXANDER K. RIDER,

of New York city, in the Stateof New York,

7 have invented certain new and useful Improvements in Pistons andPacking, of which the following is a specification:

V tion.

The accompanying drawings form a part of this specification, andrepresent several modifications.

Figure 1 is a central section, showing the invention as applied to apiston-valve. Fig.-

2 is a section through the same on the line .T T. Fig. 3 is a centralvertical section through the piston of a horizontal steam-engine. Fig. 41s an end view of the same. Fig. 5 is a-vertical section of a piston fora similar situation, but with the packing-rin gs differently mounted.Fig. 6 is a section at right angles to Fig. 5 on the line S S. Fig. 7 isa top view of the same. The other figures represent parts detached, andshow still further modifications.

Similar letters of reference indicate correspondin g parts in all thefigures wherever they occur.

Referring to Figs. 1 and 2, A is the main I body of a piston-valve; A,the face, which moves over the ports; and a, the valve-rod. The body Aextends out nearly to the interior of the inclosing-cylinder, exceptwhere it is peculiarly recessed, as shown, to receive a partialpacking-ring, D. I prefer making the packin g-ring D in severalsections, and have so represented it in thisinstance. The ends of theseveral sections or short curved pieces are fitted steam-tight together,and thus form a continuous ring of packing extending from one side ofthe solid part A nearly around the piston to the other side of the partA. Springs E, mounted in suitable recesses in the body A, act to pressthe packing away from the solid part A, and thus to extend the packingwith gentle force. The spaces at the ends of the packing which receivethe ends of the springs E tend to widen as the packing wears. These openspaces will come so near the bottom line, where the body of the pistonis always in contact with the hollowed seat, as to prevent theto beempty byreason of thefree escape of the steam therefrom across thebodyof the piston, so that the pressure of the steam under acorresponding area of the packing will be unbalanced, and will beeffective in holding out the packing. In a piston-valve the pressure ofthe steam isalways felt on one face or end of the valve and not on theother; consequently one packing-ring, D, as shown, will suffiee. Theinvention applies also to pistons in which the steam pressure alternatesfrom one side to the other, but for such application two packingringsare requiredone to serve for each side. In the use of the invention, thepacking is pressed out not simply by the gentle constant force of thesprings E, but by the same in addition to the direct pressure of thesteam on its inner face. This latter force varies with the pressure ofthe steam, and will, in ordinary cases, much exceed the former.

My construction of the piston or piston-valve and packing insures atight fit of the packing,

not only against the piston, but also against the interior of thecylinder at all points, except on the lower side of the piston.

Figs. 3 and 4 represent a piston constructed according to thisinvention, Without any continuouspart corresponding to the part A above.The packing extends quite around the piston, excepting the small spaceat the lower side where the springs apply. The two sets of packings arewide apart, and separated by a portion of the piston-body. It will beunderstood that only one of the packing-rim gs is pressed out bythe-steam to be effective at a time.

In Figs. 5, 6, and 7 is represented a correspondin g arrangement of thepacking, butwith 2 unease the packing-rings inclosed within the body ofthe piston instead of on each face. In this and all the modificationsthe application of the packing in separate pieces allows the pistonbodyA to be made in one piece without a follower. In this modification,Figs. 5, 6, 7 show the form of the recess or rabbet somewhat modified.The rabbet does not'e'xtend continuously around, but leaves each end ofeach packing-piece bearing its full width against the interior of thecylinder, and also bearing its full depth against the body of thepiston.

Figs. 8 and 9 are different views of a packin g-piece detached. Theseare intended for the modification of the pistonbody shown in Figs. 5, 6,and 7.

Figs. 10 and 11 are modifications of the packing-rings. They are formedand intended to be used in continuous pieces. A single piece extendsnearly around the piston, leaving simply a small opening, which mayreceive springs, as in the other forms. Spiral springs, partially sunkinto recesses in each end, may be employed in any instance, ifpreferred. In this modification, Fig. 10 is a central section, and Fig.11 an end view, of a continuous packingring in which there is a rabbetat each end extending continuously around, and also cavities to producean increased area of unbalanced pressure endwise. These latter cavitiesare distributed at intervals. I can, if preferred,

make these areas for end pressure also continuous, and make the ring ofa uniform section throughout, but this latter construction does notallow the same flexibility.

I would call attention to the obvious fact that the rabbet around one ofthe outer edges of a packing-ring, or a series of recesses similarlyplaced to insure a corresponding empty space, has the effect not only topromote the spread of the packing outward by the unbalanced pressureunder the packing, but also to promote the movement or pressure of thepacking axially against the adjacent face of the piston-body. It formsan unbalanced space to induce the packing to press both endwise andoutwardly.

I claim as my invention in piston-valves and pistons In combination withthe packing D D and spring or springs E, the continuous surface A in thebody A, adapted to lie in steam-tight contact with the lower part of theinterior of the inclosing-cylinder, as and for the purposes hereinspecified.

In testimony whereof I have hereunto set my hand this 27th day of March,1873, in the presence of two subscribing witnesses.

A. K. RIDER.

Witnesses:

THOMAS D. SrETsoN, WM. 0. DEY.

